Outside Heidelberg, Heidelberg
The Neckar River runs from the Black Forest to Mannheim before emptying into the Rhine. This 367 km (228 miles) long river mainly flows through the southwestern state of Baden-Württemberg, but also a short section through Hessen. The name Neckar was derived from Celtic Nikros, meaning "wild water" or "wild fellow". Along its course are ancient cities with colorful histories and amazing lush green forests and vineyards.
There are various operators offering cruises; in August 2010 we did a 9-hour cruise with the Rhein-Neckar Fahrgastschifffahrt (phew! Yes, I know these long German words can be scary... haha!)
We had a great day on the Neckar River, travelling all the way over to the historic town of Eberbach where (with our specific tour) you have 2.5 hours time to explore the town and have lunch, before the ship heads the approx. 30km back to Heidelberg.
On board there was a comfortable seating area with tables inside, or a theatre-style seating/benches up above, where during clear weather you can really appreciate the beauty along the shore, and the amazing technology behind the river's locks system (many of which you will travel up and down upon during your cruise!).
On board a small kitchen offers coffee, soft drinks, ice cream and small snacks such as cakes or potato chips/crisps.
For many years now the Neckar has been tamed with dams and locks, making it safer for the towns and villages along its shores. Although there are still occasional floods in the Neckar Valley (you can see marks on the walls of some building showing how high the water can get), they are pretty rare nowadays.
Their 2011 cruising brochure / time table can be found on their website: http://www.rnf-schifffahrt.de/Site/Fahrplaene/FahrplanStart.aspx
After visiting the schloss, take the bergbahn even up higher to the Königstuhl. You'll be rewarded with a beautiful view of Heidelberg and the Neckar River. If it's a clear day one can see all the way to Mannheim.
Once in a while, when the wind is blowing just right, you'll see paragliders starting off from the viewing point.
Unfortunately, the restaurant that offers an excellent view closed last Sept 07. Hopefully, it will re-open soon. There is a snack bar in the area serving wurst , beer and some other light snacks.
The Neckar River is considered one of Germany's most scenic drives, from Stuttgart to Heidelberg. Along this ride, you will pass many ancient castles, miles upon miles of vineyards, and several beautiful towns such as Heilbronn, Hirschhorn, Neckarsteinach.
The Rhine valley is famous for its wines and castles. A tour from Frankfurt will take you to Heidelberg plus a boat trip along the river. It's a quite nice trip.